The present invention relates generally to shoe insoles, and more particularly, to improved insoles particularly adapted for pregnant women.
Up to eighty percent of pregnant women suffer from lower back pain. In addition, hip, leg, arch and heel pain are also common. Further, there is a significant increase in the severity and frequency of back, hip, leg and foot pain between the second and third trimesters.
As a result of this pain, and further due to physiological changes associated with pregnancy, such as an increase in weight, a change in weight distribution, tissue and joint laxity, changes in hormones, etc., women progressively alter their posture and gait, in an attempt to alleviate this pain.
In addition to the relation between increasing girth and increasing body mass relative to back pain, it has been found by the inventors herein that a statistically significant correlation exists between the severity and frequency of lower back pain and increasing pressure in the arch region, resulting in overpronation, that is, excessive flattening of the longitudinal arch of the foot. Further, it has been discovered by the inventors herein that, although not correlating with back pain, there is an increase in the pressure and time spent in the forefoot region by pregnant women.
U.S. Pat. No. 4,408,402 to Looney discloses a supportive shoe and insert which compensates for changes in body weight and center of gravity which occur during pregnancy. Specifically, Looney provides increased support to specific areas of the foot. Looney teaches that, due to the increase in weight of a pregnant woman during pregnancy, the center of gravity of the woman shifts forward, thereby necessitating an increase in weight toward the back of the shoe to compensate for this forward shift. This at least suggests a rearward tilt of the insole. However, the inventors herein have found that an insole with an elevated forefoot relative to the heel, similar to that suggested by Looney, results in increased back, hip, leg and foot pain, contrary to the desired results recited in Looney.
U.S. Pat. No. 5,174,052 to Schoenhaus et al discloses a dynamic stabilizing inner sole system in which the inner sole is cut away at the center so as to form a substantially U-shaped section which extends to the heel and arch, but does not extend to the forefoot. The longitudinal center of the inner sole is cut away so that there is no effective tilt to the foot, no cushioning at the forefoot, and little cushioning at the heel. This patent also discloses a 5 varus at the heel, but this varus terminates at the center of the heel and does not extend to the lateral side. This insole was tested on pregnant women and was found not be very effective in relieving back and leg pain.